Multi-centered clinical trial to establish the safety and efficacy of Acetyl-L-Carnitine in Alzheimer's disease. The full protocol is prepared by Sigma Tau Pharmaceuticals. In addition, several assessment procedures will be completed at this site since they have proven useful in our own clinical trials. This study consists of a 1 year double blind period followed by an additional year of open trial treatment with Acetyl-L-Carnitine.